1. A New Comprehensive Detector for RHIC-II

2. Outline
Introduction
Why we are thinking about a new detector for RHIC-II
Overview of the detector design
More on specifics
Summary

3. The current group
P. Steinberg, T. Ullrich (Brookhaven National Laboratory)
M. Calderon (Indiana University)
J. Rak (Iowa State University)
S. Margetis (Kent State University)
M. Lisa, D. Magestro (Ohio State University)
R. Lacey (State University of New York, Stony Brook)
G. Paic (UNAM Mexico)
T. Nayak (VECC Calcutta)
R. Bellwied, C. Pruneau, A. Rose, S. Voloshin
(Wayne State University)
H. Caines, A. Chikanian, E. Finch, J.W. Harris, M. Lamont,
C. Markert, J. Sandweiss, N. Smirnov (Yale University)

4. Foundations of RHIC-II physics program
Properties of sQGP (Deconfinement)
Quarkonia resolution, acceptance, rates & feed-down percentages
Jet and PID high pT measurements (g-jet, jet-jet)
How do particles acquire mass?
PID at high pT, correlations, large  acceptance, -tagged jets
Structure and dynamics of the proton
Large  acceptance, jets, -jets, high pT identified particles, correlations
Is there another phase of matter? (CGC)
High-pT identified particle yields to large 
Multi-particle correlations over small & large D range

5. 1) What are the properties of matter created?
Why strongly interacting ?
Initial temperatures, system evolution, EOS ?
Study: via…
Initial T: gg-HBT
Parton density: jet tomography, flavor, intra-, inter-jet correlations
Fragmentation functions: identified leading particles
Deconfinement T: quarkonium states
- Tdiss(Y’) < Tdiss((3S)) < Tdiss(J/Y)  Tdiss((2S)) < Tdiss((1S))
Quark vs. gluon jets: jets as f(s) and (anti) particle

6. 2) How do particles acquire mass?
Contribution of gluon, sea and
valence quark to hadron mass.
Hadron formation
quark coalescence?
Is chiral symmetry
restored?
Modifications (quenching) in excited
vacuum.
Mass modifications due to excited
vacuum states, effects of chiral
symmetry?
Study via:
Modification in jet fragmentation
Identified hadrons at high pT
in fragmentation of jets in
pp and AA.

7. 3) Dynamical structure of proton
How do gluons, sea quarks, orbital angular momentum contribute to
spin of proton?
Transversity
Transversity dist. function of q andq
Sivers effect  ST  (P  k)  0
Physics beyond the standard model
New parity violating interactions etc p  s c c g W e n
D-jet
Study using:
forward W production
g-jets and di-jets
Heavy quarkonia and D measurements
High ET jets

8. 4) Is there another phase (CGC) at low-x?
Gluon saturation and color glass condensate.
What are its features ?
How does it evolve into
the QGP?
ln (1/x)
PHOBOS
low-x  forward physics
Study using:
High y identified particles
to high pT
Multi-particle correlations
- short & long range (D)
4p bulk dynamics
Dima –
Mueller Navelet Dijets

9. Comprehensive new detector @ RHIC-II
HCal and m-detectors
Superconducting coil (B = 1.3T)
Vertex tracking
RICH
Aerogel
EM Calorimeter
ToF
Tracking:
Si, mini-TPC(?),
m-pad chambers
PID:
Forward tracking:
2-stage Si disks
Forward magnet
(B = 1.5T)
Forward spectrometer:
(h = )
EMCal (CLEO)
HCal (HERA)
m-absorber
|h|  1.2
h = 1.2 – 3.5
Central detector (|h|  3.4)
Quarkonium physics
Jet physics
Forward low-x physics
Global observables over 4p
Spin physics
Characteristics of detector  allow a UNIQUE RHIC-II physics program
SLD magnet 6m

10. Why acceptance in  & pT? Broadening in h and f pp  AA pp AA
Essential for jets, high pT correlations, quarkonium, spin programs
h distributions in pp (g+jet)
Preliminary STAR results on number
correlations for pT < 2 GeV/c
Broadening in h and f pp  AA pp AA
parton fragmentation modified in dense color medium:
Dh elongation even on near side
can measure 40 GeV jets: 180k in 30 nb-1

11. Need EM & hadronic calorimetry in pp
g+jet at colliders
Direct g component
Fragmentation background
pp (spin)
isolation cuts Ehad < e Eg in cone
requires HCAL (see CDF)
e+e- in SLD
Hermetic detector (4p HCAL)  missing energy
W production: W  e(m) + n (Nadolsky, Yuan, NPB666 31), W  jet + jet

12. EM and hadronic calorimetry in AA
Isolation cuts not effective (background)  go to high ETg
 requires high rate, large acceptance
g+jet at high ETg
for ETg = 20 GeV  19,000 g + jet events in 30 nb-1
30 GeV)
with high pT PID over full away-side acceptance ||<3.4
Hadronic calorimetry - in general
improves jet energy resolution (neutral component).
removes trigger bias of EMC.
proven essential in all HEP detectors for jet physics.
not available in any RHIC experiment.

13. Quarkonia reconstruction
Melting T’s  Suppression
Tmelt(Y’) < Tmelt((3S)) < Tmelt(J/Y)  Tmelt((2S)) < TRHIC < Tmelt((1S))?
Production and nuclear absorption/shadowing studies
Resolution:
Precision Tracking + Muon Detectors
+ EMCAL + PID
Acceptance  Rates
x and cos Q* coverage
xF dependence:

14. Charmonium cc feed-down
To measure cc decay & determine feed-down to J/y
cc  J/y + g, must have large forward acceptance for g

15. Quarkonia rates with this detector
Large acceptance for electrons and muons |h|<3, Df = 2p
Precision Tracking + Muon Detectors + ECAL + PID
Au+Au min bias:
30 nb-1 plepton > 2 GeV/c for J/Y (4 GeV/c for )
Comparison to LHC
s(LHC)/s(RHIC) = 9 – 25
but Ldt (RHIC) / Ldt(LHC) > 10-20
High rates + large acceptance  xF coverage, s and A scan
Eg > 2 GeV
Eg > 4 GeV ?
BAR chart …

16. Why particle ID to high-pT?
But:
Each parton contributes to fragmentation function differently (statistical approach (Bourelly & Soffer)).
Each expected to lose different dE in opaque medium.
Presently: Modification of fragmentation function is non-specific, i.e., same for all quarks and gluons (e.g.Gyulassy et al.,nucl-th/ )
Bourelly & Soffer
Compare PID fragmentation with and without opaque medium.
Measure high pT PID two particle correlations

17. High-pT charged particle ID (p, K, p)
PID acceptance factors over upgraded RHIC detectors: f=72 (PHENIX), f=3 (STAR)
|h| < 0.5
pq,g > 10 GeV/c
New detector, 20 GeV
pq,g > 10 GeV/c
all h
STAR, 3-4 GeV
10GeV
PHENIX
f coverage p
4 GeV
rapidity
Multiply pp events by factor of ~ 8 x 1015 for
AuAu events in 30 nb-1 RHIC year

18. High pT ID’d particles and jets

19. Summary The New Comprehensive Detector designed for the
new era of UNIQUE physics at RHIC-II :
High rates
Large acceptance
High pT tracking
PID out to high pT
PID in the forward direction
Good momentum resolution
Jet/leading particle physics
Quarkonium physics
Structure and dynamics of the proton
Low-x physics
New (as yet) undetermined physics

20. The comprehensive new RHIC-II detector
HCal and m-detectors
Superconducting coil (B = 1.3T)
Vertex tracking
RICH
Aerogel
EM Calorimeter
ToF
Tracking:
Si, mini-TPC(?),
m-pad chambers
PID:
Forward tracking:
2-stage Si disks
Forward magnet
(B = 1.5T)
Forward spectrometer:
(h = )
EMCal (CLEO)
HCal (HERA)
m-absorber
|h|  1.2
h = 1.2 – 3.5
Central detector (|h|  3.4)

21. Backup slides

22. Momentum resolution
Momentum resolutions based on the tracking devices for the different regions
of pseudo-rapidity and the forward spectrometer section.

23. Charged Particle PID
Charged hadron particle identification as a function of momentum using the ToF (time-of-flight), Aerogel 1 (n =1.01), Aerogel 2 (n =1.05), and gas-RICH (n= ) detectors. The horizontal lines indicate where each particle can be identified based on combinations of signals.

24. Central tracker layout
Detector Radius(cm) Halflength (cm) Sigma r-phi(cm) Sigma z(cm) Thickness(cm)
Vertex
(APS or
Hybrid pixels)
Main Si-strip
OrMain mTPC
(mylar+gas)
High pT track
micropattern G10 +
Gas +
Mylar
Position, segmentation in radius (r) and azimuthal angle (f),
and thicknesses of the various central tracking detectors.